This invention relates generally to corona charger apparatus, and more particularly to corona wire in the form of a tape assembly for corona charger apparatus.
In many types of printing apparatus, such as for example electrostatographic reproduction devices, it is common practice to use corona charger apparatus to provide an electrostatic field for various purposes such as uniformly charging a dielectric support or transferring a marking particle developed image from the dielectric support. Typical corona charger apparatus include a thin wire, fabricated of tungsten for example, to which a high voltage is applied to generate ions or charge current to charge a surface (dielectric support or receiver member) located closely adjacent to the charger apparatus. If desired, an electrically biased grid may be interposed between the wire and the surface to control the charge deposited on the surface. The corona wire is tightly suspended between two insulating blocks which also provide a support for a connection to a high voltage source. Tension in the corona wire must be accurately set in order to prevent undesirable sagging of the wire if the tension is insufficient or breakage of the wire if the tension is too high. Since the corona wire is thin, it is fragile and setting and maintaining proper tension is difficult.
Further, while corona charger apparatus are noted for their ability to produce a relatively uniform charge deposit on a surface, the wire of the charger apparatus deteriorates over time. Such deterioration results in non-uniformity of the charge deposit with, for example, a corresponding degradation of the information reproduced by an electrostatographic reproduction device employing such corona charger. Accordingly, the corona charger apparatus wire must be periodically replaced to maintain high quality reproductions.